Last week, the New Scientist traced the claim back to an article it ran in 1999, reporting the view of the leading Indian glaciologist Syed Hasnain, that all the glaciers in the central and eastern Himalayas could disappear by 2035.

This claim was not repeated by Mr Hasnain in peer-reviewed literature, but was picked up in a report by WWF, the environmental campaigning group, which was the source for the inclusion of the claim by the IPCC.

The claim is pretty strong stuff, as the disappearance of the glaciers would condemn hundreds of millions of people to water shortages.

This is not as bad as the Climate gate emails, relating as it does to a relatively minor claim. It will encourage the Indian government, which recently commissioned a report to show that the Himalayan glaciers are not melting as fast as some feared.

But it is another fillip for the sceptics. Episodes like this are damaging to the credibility of climate scientists, and are frustrating for the vast majority of those who are careful, accurate and conscientious in their methods.